Circuit breaker



M. V. ZUBATY CIRCUIT BREAKER Dec. 13, 1966 5 Sheets-Sheet 1 Filed Feb.16, 1965 De. 13, 1966 M. v. zUBATY 3,29938 CIRCUIT BREAKER Filed Feb.1e, 1965 .'3 Sheets-Sheet i3 /ff f M. V. ZUBATY CIRCUIT BREAKER Dec. 13,1966 3 Sheets-Sheet 3 Filed Feb. 16, 1965 2%@ 721/22 l( ELI/Egg?? /9'faWA/E/S'.

United States Patent O Filed Feb. 16, 1965, Ser. No. 433,091 8 Claims.(Cl. 2011-116) 'Ihis invention relates generally to electric circuitbreakers and more pa-rticularly to an improved multi-pole, trip free,common trip type of circuit breaker.

Multi-pole, automatic, electric circuit breakers of the type with whichthe invention is concerned are often used to protect multi-phase branchcircuits which are connected at one end thereof to a multi-phase powersupply and at the other end to a multi-.phase load, for example, threephase motors and other like multi-phase devices. The circuit breakersgenerally comprise a plurality of electrically isolated pairs ofseparable contacts, a releasable operating mechanism for eifectingsimultaneous separation of the respective pairs of contacts and a tripdevice which is responsive to predetermined conditions in any one of thephases of the electrical circuit to effectuate the release of theoperating mechanism of the circuit breaker and to open each of thephases of the branch circuit.

Typically, the trip device of such circuit breakers comprises a latchmechanism which is operatively connected to a current responsive memberand is operable to effect the engaging and disengaging movement of thelatch. In operation, the latch must be relatively strong mechanically inorder to retain the operating mechanism in the closed condition andsuicient contact pressure must be applied to insure the properelectrical contact of the circuit breaker contacts. In addition, themechanism must be readily releasable upon relatively slight movement ofthe latch proper and in response to -a slight variation in the conditionof the current responsive member in any one of the plurality of phases.vThe current responsive member must be sensitive to a relatively smallincrement of change in current above a preselected maximum and have aphysical response characteristic which is capable of releasing the latchin the manner described above. In certain prior art multiple circuitbreakers for use with a multi-phase branch circuit, the contact pressureof the contacts has been directly related to the number of contactswhich are located within the circuit breaker. Thus difficulty has arisenin providing the proper contact pressure for each individual pair ofcontacts and the current carrying requirement impressed thereon.

' Also in certain other of the prior art circuit `breakers of this type,the latch mechanism has been connected through a llexible member to acontact carrying element wherein the flexible element is required to Hexin accordance with t-he amount of contact pressure which is to beapplied. In the type of ilexible member which has been used in theypast, it has been found that, through the heat of the unit, the llexibleelement has been fatigued and often fractures in use, thereby causingthe circuit breaker to fail. While t-he breaker may fail safe, it isnecessary that the breaker be replaced thereby causing the circuit to beout of use, both for the time that the element is fractured and for thetime that is required to replace the breaker. Also certain otherproblems have arisen in the prior art breakers in the force system setup within the breaker in order to keep the proper contact pressure ricebetween the contacts and it is with these forces that the invention isdirected in addition to the aforementioned areas.

One of the important considerations of multi-phased breakers of thistype is to provide a reliable and fast acting breaker wherein each ofthe phases of the multi-phased circuit is effectively and rapidly brokenwithout the dangerof one of the phases remaining in contact. Withcertain of the prior art devices, each .phase was independently sensedto provide an independent trip for the corresponding portion of thebreaker, It is desirable that a single member sense the conditions ofall three phases of the branch circuit conjunctively rather than haveindividual sensers for the individual circuits and introducing theproblem of relating all of the conditions of the circuit to a singlelatch element. Thus it is desirable that individual units produce asignal condition according to the conditions within the branch circuitand a single member sense the signal condition to activate one memberwhich will in turn disengage all of the plurality of pairs of contactsin each phase of the branch circuit. This action should be relativelyfast and reliable for the aforementioned reasons and must Ibe capable ofwithstanding severe vibra- Ation and transient effects in theenvironment with which the circuit breaker is involved. Also, thecircuit breaker should be capable of withstanding relatively highinstantaneous fault current over and above the normally encounteredoverload current to which the circuit breaker is responsive. Thus afailure in one phase should produce substantially the same trip resultin the circuit breaker as a failure in all of the phases of amulti-phase circuit.

In utilizing a multi-pole circuit breaker fabricated according to theprinciples of the present invention, the user is insured of positiveoverload protection for relatively loW current multi-phase circuits byutilizing a trip device for the contacts which is sensitive to a lowfault in any one of the phases, a large fault in any one of the phasesor any combination of the two. The overload current is sensed and asignal condition produced by a heater element which is electricallyconnected in each of the branch circuits of the multi-phase system. Inturn, this signal condition is sensed by a bimetallic element which isconnected to a trip lever assembly common to all of the phases of thebranch circuit. The latch mechanism has been constructed of a pair ofresiliently biased members, one of which carries a movable contactelement and the other of which is engageable with the trip levermechanism, thus providing a ilexible connection between the two elementsof the latch mechanism. With certain modifications, the circuit breakerunit of the instant invention is of the general type disclosed in PatentNo. 3,145,281,

issued to the common assignee on August 18, 1964, and entitledMulti-Pole Circuit Breaker With Trip Devices Located In the Housing Of aSingle Pole.

Accordingly, it is one object of the present invention to provide animproved automatic multi-pole circuit breaker for use in protectingrelatively low current multi-phase circuits.

Another object of the present invention is to provide a multi-polecircuit breaker that operates substantially instantaneously upon arelatively small current overload.

Another object of the present invention is to provide an improvedcircuit breaker having improved overload sensing features.

It is still a further object of the present invention to 3 provide animproved circuit breaker having improved means for applying contactpressure to the pairs of contacts thereof.

It is still another object of the present invention to provide a circuitbreaker having improved means for correlating overload conditions in anyone of or all of the phases of a multi-phase circuit.

It is still another object of the present invention to provide a circuitbreaker having improved force distribution characteristics within thestructural elements of the circuit breaker.

It is still a further object of the present invention to provide acircuit breaker having improved latch trip features wherein the responseof the circuit breaker is greatly enhanced.

It is still a further object of the present invention to provide amulti-pole circuit breaker which is simple to construct and inexpensiveto manufacture.

Further objects, features, and advantages of this invention will becomeapparent from a consideration of the following description, the appendedclaims and the accompanying drawing in which:

p FIGURE l is a top, partially broken away view of a multi-pole circuitbreaker incorporating certain principles of the present invention andillustrating the heater and trip assemblies thereof;

FIG. 2 is an elevational side view of the multi-pole circuit breaker ofFIGURE l taken along line 2-2 thereof and particularly illustrating thetrip lever and latching assembly;

FIG. 3 is an elevational view of the circuit breaker assembly of FIG. 2and taken along the line H3-3 thereof and particularly illustrating theheater assembly; and.

FIG. 4 is another cross-sectional view of the circuit breaker assemblyof FIG. 2 taken along line 4-4 thereof.

Referring now to the drawings, there is illustrated a multi-pole, tripfree electric circuit breaker 10, constructed in accordance with apreferred embodiment of the present invention and comprises aninsulating housing 12 fabricated of ceramic or other like insulatingmaterial, portions of which are held together by screws 14, rivets 15 orother like fastener means. The front is closed by means of a metal covermember 13 and a wafer like insulating means 16 suitably insulates theinner portions of the breaker from the cover 13 and suitably seals thejuncture between certain portions of the circuit breaker housing 12 andthe cover 13. The housing generally comprises a plurality ofinterconnected sections 18, 20 and 22, which house the various portionsof the circuit breaker associated with each of the phases of themultiphase circuit. The sections are divided by suitable dividing means24 which may take the form of integrally molded projections dependingfrom the interior of the housing. The projections 24 may also serve tofasten the upper portion of a yoke member 26 which is utilized toseparate the three sections illustrated and also to sup port theelements within the circuit breaker assembly as will be hereinafterexplained.

The lower portion of the U-shaped frame is rigidly fastened to the cover13 of the circuit breaker housing 12 by means of rivets 28, and a Washermember 30. The housing 12 may be held together by a suitable means suchas rivets or screws passing through the two halves of the housing. Theupper portion of the housing 12 is provided with a plurality of pairs ofterminals 30-32, 34-36, and 38-40 which are suitably fastened inposition relative to the housing, by means of a plurality of pairs-ofscrews, 42, 44 and 46. A plurality of insulating barriers 47, 49, 51 and53 suitably insulate the pairs of conductors of each phase relative toeach other and also provide additional rigidity to the structure. Withsuitable conductors connected to the terminals, such as terminals 34,36, the current will pass through the circuit breaker sectioncorresponding thereto, as from terminal 36 and will exit from thebreaker, as at terminal 34. Thus a 4 control of the current in each ofthe branches by means of the circuit breaker will be efectuated. Whileonly the center section of the breaker will be described, it is to beunderstood that each of the sections is substantially identical inmaterial details and any exception will be specifically noted.

The mounting screws 44 pass through a generally T- shaped section 48 and50 of the terminals 34, 36, respectively, and the lower portion 50provides a mounting surface for a fixed contact 52, which is adapted tomate with a movable contact 54. The three pairs of terminals -30-32,34-36 and 38-40 are adapted to be connected to opposite sides of anexternal 3-phase electrical circuit so that current normally flows fromone terminal through the circuit breaker to the associated terminal.With the contacts of any one pole in the tripped or open position due toa current overload condition, an interruption of the current ilowthrough the circuit breaker 10 will be effected, as is seen in FIG. 2.The movable Contact 54 is mounted on a rotatable latch assembly 58, thedetails of which will hereinafter be described. The connection throughthe circuit breaker is made by a pigtail conductor 60, one end of whichis connected to the latch assembly 58 and the other end is connected toa heater assembly 62. As was stated above, only the center unit of thecircuit breaker will be described for simplicity. However, it is to benoted that many of the assemblies described in conjunction with thedescription of FIG. 2 have counterparts in the other two portions of thecircuit breaker. Where these assemblies have not been given separatereference numerals, they will be given the primed or double-primedreference numeral of the corresponding element in the center portion.

From the heater assembly 62, the current flows upwardly to the lowerportion 48 of terminal assembly 34 and thus outwardly to the otherconductor of the pair of conductors connected to the one phaseillustrated. The control of the latch assembly is effected through aheat sensitive trip lever mechanism 66 which engages a portion of thelatch assembly 58 to hold it in position until such time as the currentoverload condition is sensed and the trip lever assembly releases thelatch assembly thereby opening contacts 52, 54. The manual resetoperation of the latch assemblly is etfectuated through a manual plungerassembly 70, which is suitably connected thereto. Asbest seen in FIG. 2,the manual plunger assembly 70 extends externally of and is slidablysupported in a threaded nipple 72 which is integrally formed with themetal cover member 13 mounted on the lower portion of the housing 12.

The plunger assembly 70 includes `a compression spring', 76 which 4isadapted to albut at one end thereof against a. shoulder 78 formerintegrally with a sleeve member 80A and the other end of -tfhe .springis adapted t'o abut inwardly extending shoulder portion 82 formed on thelower por-- tion lo'f the housing member 12. In this way the plungerass'emlbly is held in the outwardly lbiased position. The; plungerassembly 4f-urther includes `a manually actuable plunger member 84 whichmay be integrally fonmed withl the sleeve or formed separately, asillustrated in FIG.. 2. The plunger 4member 84 is connected to an outer'plunger .shaft 88 by means of a pin '90 passing through lboth theplunger member 84 and the outer shaft member 88. It is to be noted thatthe switch illustrated in FIG. 2 is in the reset position, that is,wherein the contacts 52, 54 are closed and the trip lever bar assembly66 is in engagement with the latch assembly 58 to resiliently biascontacts 52, 54 together.

The plunger 'operator assembly 70 fur-ther comprises an `inne-r plunger,shaft 92 which is connected to the outer plunger shaft 88 by means of alost motion connecti-on 94 which generally comprises 4a rivet 94 carriedIin an elongated slot 96, whereby the connection is made between -innerplunger shaft memlber 92 and the outer plunger shaft member 88. Theinward and outward movement of the plunger assembly 701 is guided bothby the sliding engagement of the sleeve 80 within the nipple 72 and alsoby means of a pin 98 which lis rigidly fixed in the nipple assembly 72and slidably engages an elongated slot y100 #formed in the outer plungershaft member 88.

The outer plunger :shaft 88 is held in its retracted position by atoggle lever assembly 104 having a biasing arm 106 which tends to bias atoggle lever 108 in a direction toward the outer plunger shaft 88. Thetoggle lever 108 is pivotally mounted on a frame member .110 by means ofa pivot pin 112 and the connection between lever arm 106 and togglelever 108 is made by pin 114. The toggle lever member has a rollermember `118 formed at one end thereof which is adapted to engage acutout portion 120 formed in outer plunger shaft 88. With the rollermember 118 engaging slot 120, the plunger assembly is maintained in theretracted position against the bias of the compressed spring 76. Theconnection between lever arm 106 and toggle lever 108 is made rigidthrough a cutout portion `formed in one end of the lever arm 106 whichengages pin 112, thus forming -a pivotal connection for the toggle leverassembly 104 about pin 112. The biasing 'force which is utilized t-omaintain engagement between roller `11-8 and cutout 120 is provided byspring member 122, as will be seen as t-he description proceeds. It isto be understood that the circuit breaker assembly contains only -asingle plunger assembly 70 and toggle lever assembly `104, therebymaintaining the circuit breaker in the set condition with a minimum ofparts and allowing the resetting of the tripped mechanism with themotion of a single plunger, `as for example plunger 84. Moreover, asin-gle trip lever mechanism 66 is provided with separate sensors foreach phase for the trip action.

The latch assembly 58 which supports the mov-able contact 54, comprises1a generally L-shaped contact support element 126 having the contact 54.soldered or welded to an upper surface of one leg thereof. 'The otherleg is provided with a flexible conductor element 128 soldered or weldedthereto to conduct t-he current to another portion of the circuitbreaker assembly, as will be hereinafter explained. The one leg 127 isconnectedto a pivotal pin element 132 which is supported in the .frame26 by means of a hinge member 134 pivotally mounted on pin 132. Thus, asthe L-shaped member 126 and hinge member `134 pivot on pin 132, thecontact element 54 will be moved toward and away `from the hxed contactmember 52 in an arcuate movement. It is t-o be understood that, whileonly one latch assembly 58 is illustrated in FIG. 2, there is acorresponding latch assembly 57 and 59 for each phase of the multi-phasecircuit, respectively. This may best be seen from the view illustratedin FIGS. 1 and 4 wherein is illustrated the fact that a hinge membercorresponding to hinge `member 134 is provided for each of the poles ofthe breaker .10.

The L-shaped'contact carrying member 126 is r-esiliently biased into theclosed position by means of a compression spring 140, which is carriedin an open, `generally upwardly extending tubular member 141 mounted ona contact biasing rod member 142 pivotally mounted on pin 132 by meansof a generally U-shaped extension member `144 connected thereto at theends thereof and a pair of hinge extensions 145 integrally `formed withrod member 142 (see FIGURE l). One end 146 of extension member 144 hasprovided thereon a shoulder member 148 which is adapted to engage aportion of the trip lever assembly 66, thereby main-taining a biasingforce on spring element 140. Thus, with the trip lever bar assembly 66engaging the upper surface of the shoulder member 148, the. other end ofthe latch assembly 58 will be urged upwardly with the spr-ing 140 intobiasing engagement with the upper leg 127. In this way the contacts 52and 54 will be held in intimate relationship with each other. As in thesituation of the hinge member 134the rod member 142 :is common to aplural- 6. ity of tubular members, one for each pole, and each having aspring member carried therein.

As the shoulder element `148 is released by trip lever assembly 66, thespring 140 tends to release the pressure on leg 127 thereby relievingthe biasing pressure on the contact element 54. As was s-tated above,spring element 122 resiliently urges roller member 118` into cutoutportion and the other end of spring member 122 is fastened to anextension of the rod member 142 thereby tend-ing'to urge the rod member142 downwardly to provide a resilient biasing force on the shoulderportion 148 upwardly against trip lever assembly 66. -Upon the releaseof the latch assembly 58 by the trip lever assembly 66, the yforce ofspring 122 is relieved .from toggle lever assembly thereby allowing thewheel member 1,18 to disengage `from the cutout portion 120. With thewheel member 1118 disengaged, the plunger assembly 70 will moveoutwardly of the housing 12 by means of spring 7.6, thereby urging theinner plunger shaft 88 downwardly along with latch assembly 58 andcontact element 54. Thus the movable contact element 54 is separatedfrom the fixed contact element 52. As the bias member 142 movesdownwardly on being released, a lower face 147 thereof engages a tip 149`formed on the lower leg of L- shaped member 126 thereby limiting therelatively movement between members 126 and 142. In this manner thespring is effectively oonned therebetween and the further downwardmovement of the latch assembly 58 is caused by a pair of spring members176', 17 6 lconnected to an extension of rod member 142 at one end andtrip lever assembly 66 at the other. The complete rotation of theassembly 58 is prohibited by the engagement of a portion of rod member142 with the support member 26.

The action of the latch assembly 58 is control-led by means of the triplever assembly 66, which is thermally responsive to the heat generatedby current flowing through -a heater assembly 150. The heater assemblygenerally comprises a heater unit 151, 152, 153 for each of the phasesto be controlled, as best seen in FIG. 3, and has a pair of outside legs154, 156 and a middle leg 158 which is connected to the other end of theexible conductor 60. It is to be noted that the exible conductor 60 iscovered with a flexible nylon, or other type of insulating material,sleeve in order to prevent -a short circuit with any of the componentsof the circuit breaker. Thus, in FIG. 2, current enters from terminal 36and flows tlirough closed contacts 52, 54 through flexible conductor 60to the central legs 158, 159 of the heater 150 and out through the outerlegs 154, 156 to terminal 34 by means of terminal member 48. A suitablespring member 160 has been fastened to the heater assembly 150 as a partof assembly 62 and engages a portion of the frame 26 tto provide thenecessary spring bias between trip lever assembly 66 and heater assembly150.

As the heat is generated in heater assembly 150, a bimetallic element162 of trip lever assembly 66, having a fixed end 164 and a freelymovable end 166, is placed in close heat transfer relation with heater150. As the heat is transferred from the heate-r 150 to the bimetallicelemen-t 162, the freely movable end 166 tends to move away from thep-lunger assembly 70, thereby moving a trip lever bar 170, fastenedthereto, away from shoulder member 148. The bimetallic element 162 isfastened to the tri-p lever bar 170 at a central portion thereof bymeans of a rivet 172. An inward bias for the trip lever assembly isprovided by means of a pair of springs 176', 176 which are connected atone end thereof to a pivot pin 178 and at the other end thereof to theextension of the rod member 142, as described above. The pivot pin 178is rigidly fasten-ed to the trip lever bar by means of a bracket 180which has been suitably attached the-reto as by rivet 172 and a secondrivet 182.

The engagementl between the trip lever bar 170 and the shoulder portion148 is provided` by means of a shoulder face element 186 which isattached to the trip lever bar by means of .a rivet 188. The lmember 186has been provided with a downwardly -facing surface 190, which isadapted to engage the upper surface of shoulder member 148, .as is seenfrom FIG. 2. As bimetallic element 162 extends to the right due to theheating provided through heater 150, the surface 190 will be drawn awayfrom above the shoulder element 148, thereby releasing the latchassembly 58 and the action of disengagement las described above, willoccur. The heater assembly 150 is attached to the terminal member 48 atthe top of the heater assembly by any suitable -means such as solderingor welding, and a Calibrating screw 194 has been provided in the wall ofIhousing mem-ber 12 to inwardly urge the lower portion of heater 150toward the bimetallic element 162 -against the action of spring 160.Thus, a control of the amount of heat required to activate bimetallicelement 162 has been provided.

As stated above, the invention relates to a multi-pole circuit breakerwherein a plurality of phases .are controlled by means of a pair ofcontacts `52, 54. Thus it is necessary that three pairs of contacts52-54, 194-196 and 198-200 are provided to provide the necessary controlfor the three phases of a ibranch circuit, in the case of a 3- phasesystem. Also, a plurality of heater assemblies 150, 152 and 153 areprovided to provide heat to a plurality of bimetallic elements 162, 162and 162" for each of the three heaters, 150, 152 and 153 of each leg oft-he 3- phase system. However, it is to be noted that only one shoulderelement 148 has been provided and correspondingly only one face member186 has been provided inasmuch as a single activation of the trip barassembly 66 is needed to disconnect -all of the contacts of the system.Thus, a portion of latch assembly 58 will be provided continuously forall three of the poles of the unit and a plurality of springs 140 willbe provided, one for each pair of contact elements of the assembly.Thus, as current in any one leg of the branch circuit heats itscorresponding heater unit, as for example, heater element 150 toactivate bimetallic element 162, the trip lever assembly will beactivated thereby unlatching the latch assembly 58.

While it wil-l be apparent that the embodiment of the invention hereindisclosed is well calculated to fulfill the objects of the invention, itwill be appreciated that the invention is susceptible to modiication,variation and change without -departing from the proper scope or fairmeaning of the sub-joined claims.

What is claimed is:

1. An electric circuit breaker comprising a housing, a stationarycontact within said housing, a movable conrtact engageable with saidlstationary contact, a releasable plunger assembly for eiecting movementof the movable contact into engagement with said stationary contact, atrip device having a set conditi-on for maintaining said contacts inengagement and a tripped condition for releasing :the engagement betweenthe stationary and movable contacts in said tripped condition inresponse to a preselected condition in said breaker, and means operablyconnected to said plunger assembly for relating the motion of saidassembly mechanism to said movable contact and engageable with said tripdevice for urging the engagement of said movable and stationary contactsduring at least a -portion of said motion and relieving said movablecontact from said enga-gement when said preselected conditions aresensed including support means supporting said movable contact inpivotal relation to said plunger assembly and biasing means includingresilient means resiliently engageable with said support means forurging said movable contact into engagement with said stationarycontact, said biasing means including pivot arm means pivotallyconnected to said operating mechanism and having one end releasably inengagement with said trip device and a portion of the other end thereofincluding means for lixedly supporting said resilient means on saidpivot arm means.

2. An electric circuit breaker comprising a housing, a stationary-contact within said housing, a movable contact engageable with saidstationary contact, a releasable plunger assembly for eiecting movementof the movable contact into engagement with said stationary contact, atrip device having a set condition for maintaining said contacts inengagement anda tripped condition for releasing the engagement betweenthe stationary and movable contacts in said tripped condition inresponse to a preselected condition in said breaker, and means operablyconnected to said plunger .assembly for relating the motion of saidassembly mechanism to said movable contact and engageable with said tripdevice for urging the engagement of said movable and stationary contactsduring at leasta portion of said motion and relieving said movablecontacts from sai-d engagement when said preselected conditions aresensed including support means pivotally connected to said assembly forsupporting said movable contact in pivotal .relation to said plungerassembly, biasing means resiliently-'engageable with said support meansfor urging said movable contact into engagement with said stationarycontact, said biasing means including an arm pivotally connected t-osaid operating mechanism at a central portion and having one endreleasably in engagement with said -trip device, a compression spring,and means formed -at the other end of said arm for supporting saidspring in resilient lreleasable engagement with said support means.

3. An electric circuit breaker comprising a housing, -a stationarycontact within said housing, a movable contact engageable with saidstationary contact, a releasable plunger assembly for effecting movementof the movable contact into engagement with said stationary contact, atrip device having a set condition for maintaining said contacts inengagement and a tripped condition for releasing the engagement betweenthe stationary and movable contacts in said tripped condition inresponse to a preselected condition in said breaker, and means operablyconnected to said plunger assembly for relating the motion of saidassembly mechanism to said movable contacts and engageable with saidtrip device for urging the engagement of said movable and stationarycontacts during at least a portion of said motion and relieving saidmovable contacts from said engagement when said preselected conditionsare sensed including a generally L- shaped support means pivotallyconnected to said assembly .at the end of one leg thereof and supportingsaid movable contact on an upper surface thereof in pivotal relation tosaid plunger assembly, biasing means resiliently engageable with saidsupport means for urging said movable contact into engagementvwith saidstationary contact, said biasing means including an arm pivotallyconnected at a central portion thereof to said operating mechanism andhaving one end releasably in engagement with said trip device, acompression spring and cup means formed at the other end of said arm:Eorsupporting said spring in resilient engagement with said supportmeans, said cup means having a portion thereof adapted to engage aportion of said L-shaped support `means in said tripped condition formaintaining said spring in said cup means and engaging said L-shapedmember.

4. vAn electric circuit breaker comprising a housing, a stationaryContact within said housing, a movable contact engageable with saidstationary contact, a releasable plunger assembly for eiecting movementof the movable contact into engagement with said stationary contact, atrip device having a set condition for maintaining said contacts inengagement and a tripped condition for releasing the engagement betweenthe stationary and movable contacts in said tripped condition inresponse to a preselected condition in said breaker, and means operablyconnected to said plunger assembly for relating the motion of saidassembly mechanism to said movable contacts and engageable with saidtrip device for urging the engagement of said movable and stationarycontacts during at least a portion of said motion and relieving saidmovable contacts from said engagement when said preselected conditionsare, sensed including a generally L- shaped support means pivotallyconnected to said assembly at the end of one leg thereof and supportingsaid movable contact on .an upper surface thereof in pivotal relation tosaid plunger assembly, biasing means resiliently engageable with saidsupport means for urging said movable contact into engagement with saidstationary contact, said biasing means including an arm pivotallyconnected at a central portion thereof to said operating mechanism andhaving one end releasably in engagement with said trip device, acompression spring and cup means formed at the'other end of said arm forsupporting said spring in resilient engagement with said one leg of saidsupport means, said L-shaped member having a shoulder portion formed `atthe end of the other leg thereof, said shoulder portion being adapted toengage a lower surface of said cup means in said tripped condition forlimiting the pivotal movement of said cup means with respect to saidsupport means and maintaining said spring in engagement with said oneleg.

5. A multipole electric circuit breaker comprising a housing, aplurality of electrically isolated poles within said housing, aplurality of stationary contacts Within said poles, respectively, aplurality of movable contacts engageable with each respective stationarycontact, a single releasable plunger assembly for effecting movement ofthe movable contacts into engagement with said stationary contacts, atrip device, having a set condition for maintaining said contacts inengagement and a tripped condition for releasing the engagement betweenthe stationary and movable contacts in said tripped condition inresponse to ya preselected condition in said breaker, and means operablyconnected to said plunger assembly for relating the motion of saidassembly mechanism to said movable contacts and engageable with saidtrip device for urging the engagement of said movable and stationarycontacts during at least a portion of said motion and relieving saidmovable contacts from said engagement when said preselected conditionsare sensed including support means supporting said movable contacts inpivotal relation to said plunger assembly and biasing means includingresilient means resiliently engageable with said support means forurging said movable contacts into engagement with said stationarycontacts, respectively, said biasing means including pivot arm meanspivotally connected to said operating mechanism and having one endreleasably in engagement with said trip device and a portion of theother end thereof including means for xedly supporting said resilientmeans on said pivot arm means.

6. A multipole electric circuit breaker comprising a housing, aplurality of electrically isolated poles within said housing, aplurality of stationary contacts within said poles, respectively, aplurality of movable contacts engageable with each respective stationarycontact, a single releasable plunger assembly for effecting movement ofthe movable contacts into engagement with s-aid stationary contacts, atrip device having a set condition for maintaining said contacts inengagement and a tripped condition for releasing the engagement betweenthe stationary and movable contacts in said tripped condition inresponse to a preselected condition in said breaker, and means operablyconnected to said plunger assembly for relating the motion of saidassembly mechanism to said 4movable contacts and engageable with saidtrip `device for urging the engagement of said movable and stationarycontacts during at least a portion of said motion and relieving saidmovable contacts from said engagement when said preselected conditionsare sensed including support means pivotally connected to said assemblyfor supporting said movable contacts in pivotal relation to said plungerassembly, biasing means resiliently engageable with said support meansfor urging said movable contacts into engagement with said stationarycontacts, respectively, said biasing means includl0 ing an arm pivotallyconnected to said operating mechanism at a central portion and havingone end releasably in engagement with :said trip device, a compressionspring, and means formed at the other end of said arm for supportingsaid spring in resilient releasable engagement with said support means.

7. A multipole electric circuit breaker comprising a housing, aplurality of electrically isolated poles within said housing, aplurality of stationary contacts within said poles, respectively, aplurality of movable contacts engageable with each respective stationarycontact, a single releasable plunger assembly for effecting movement ofthe movable contacts into engagement with said stationary contacts, atrip device having a set condition for maintaining said contacts inengagement and a tripped condition for releasing the engagement betweenthe stationary and movable contacts in said tripped condition inresponse to a preselected condition in said breaker, and means operablyconnected to said plunger assembly for relating the motion of said`assembly mechanism to said movable contacts and engageable with saidtrip device for urging the engagement of said movable and stationarycontacts during at least a portion of said motion and relieving saidmovable contacts from said engagement when said preselected conditionsare sensed including a generally L-shaped support meanspiv-otallyconnected to said assembly at the end of one leg thereof andsupporting said movable contacts on an upper surface thereof in pivotalrelation to said plunger assembly, biasing means resiliently engageablewith said support means for urging -said movable contacts intoengagement with said stationary contacts, respectively, said biasingmeans including an arm pivotally connected at ya central portion thereofto said operating mechanism and having one end releasably in engagementwith said trip device, a compression spring and cup means formed at theother end of said arm for supporting said spring in resilient engagementwith said support means, said cup means having 'a portion thereofadapted to engage a portion of said L-shaped support means in saidtripped condition for maintaining said spring in said cup means andengaging said L-shaped member.

8. A multipole electric circuit breaker comprising a housing, aplurality of electrically isolated poles within said housing, aplurality of stationary contacts within said poles, respectively, yaplurality of movable contacts engageable with each respective stationarycontact, a single releasable plunger assembly for effecting movement ofthe movable contacts into engagement with said stationary contacts, atrip device having a set condition for maintaining said contacts inengagement and a tripped condition for releasing the engagement betweenthe stationary and movable contacts in said tripped condition inresponse to a preselected condition in said breaker, and means operablyconnected to said plunger assembly for relating the motion of saidassembly mechanism to said movable contacts and engageable with saidtrip device for urging the engagement of said movable and stationarycontacts during at least a portion of said motion and relieving saidmovable contacts from said engagement when said preselected conditionsare sensed including a generally L-shaped support means pivotallyconnected to said lassembly at the end of one leg thereof and supportingsaid movable contacts on an upper surface thereof in pivotal relation tosaid plunger assembly, biasing means resiliently engageable with saidsupport means for urging said movable contacts into engagement with saidstationary contacts, respectively, said biasing means including an armpivotally connected at a central portion thereof to said operatingmechanism and having one end releasably in engagement with said tripdevice, a compression spring and cup means formed at the other end ofsaid arm for supporting said spring in resilient engagement with saidone leg of said support means, said -shaped member having a shoulderportion formed at 11- the end of the otherleg thereof, said shoulderportion being adapted to engage a lower surface of said cup means insaid tripped condition for limiting the pivotal movement of said cupmeans with respect to said support means and maintaining said spring inengagement with 5 said one leg.

. References Cited by the Examiner LUNITED STATES PATENTS 2,612,2962,686,241 8/1954 Straub et al. 20o- 116 12 Krieger `200-116 Mascioli etal. 200-116 Ingwersen et al. 200-116 Brackett 200-116 Wood 200-116Brackett 200-116 Ingwersen 2001-116 Brandenburg 200-124 BERNARD A.GILHEANY, Primary Examiner.

1. AN ELECTRIC CIRCUIT BREAKER COMPRISING A HOUSING, A STATIONARYCONTACT WITHIN SAID HOUSING, A MOVABLE CONTACT ENGAGEABLE WITH SAIDSTATIONARY CONTACT, A RELEASABLE PLUNGER ASSEMBLY FOR EFFECTING MOVEMENTOF THE MOVABLE CONTACT INTO ENGAGEMENT WITH SAID STATIONARY CONTACT, ATRIP DEVICE HAVING A SET CONDITION FOR MAINTAINING SAID CONTACTS INENGAGEMENT AND A TRIPPED CONDITION FOR RELEASING THE ENGAGEMENT BETWEENTHE STATIONARY AND MOVABLE CONTACTS IN SAID TRIPPED CONDITION INRESPONSE TO A PRESELECTED CONDITION IN SAID BREAKER, AND MEANS OPERABLYCONNECTED TO SAID PLUNGER ASSEMBLY FOR RELATING THE MOTION OF SAIDASSEMBLY MECHANISM TO SAID MOVABLE CONTACT AND ENGAGEABLE WITH SAID TRIPDEVICE FOR URGING THE ENGAGEMENT OF SAID MOVABLE AND STATIONARY CONTACTSDURING AT LEAST A PORTION OF SAID MOTION AND RELIEVING SAID MOVABLECONTACT FROM SAID ENGAGEMENT WHEN SAID PRESELECTED CONDITIONS ARE SENSEDINCLUDING SUPPORT MEANS SUPPORTING SAID MOVABLE CONTACT IN PIVOTRELATION TO SAID PLUNGER ASSEMBLY AND BIASING MEANS INCLUDING RESILIENTMEANS RESILIENTLY ENGAGEABLE WITH SAID SUPPORT MEANS FOR URGING SAIDMOVABLE CONTACT INTO ENGAGEMENT WITH SAID STATIONARY CONTACT, SAIDBIASING MEANS INCLUDING PIVOT ARM MEANS PIVOTALLY CONNECTED TO SAIDOPERATING MECHANISM AND HAVING ONE END RELEASABLY IN ENGAGEMENT WITHSAID TRIP DEVICE AND A PORTION OF THE OTHER END THEREOF INCLUDING MEANSFOR FIXEDLY SUPPORTING SAID RESILIENT MEANS ON SAID PIVOT ARM MEANS.